RESUMO
A technology capable of producing large-area pressure-tolerant x-ray entrance windows of submicrometer thickness is presented. It is based on successive tungsten griddings to support a multilayered membrane consisting of polyimide, aluminum, and aluminum nitride. The aspects of design and fabrication processes are discussed with emphasis on the window foil fabrication. The performance of the windows is presented in terms of x-ray transmission, gas leak, pressure endurance, and radiation hardness properties.
RESUMO
In order to fabricate entrance windows for soft x-ray detectors, various technologies have been developed. Depending on the x-ray-detector type and the environment in which the windows are used, entrance windows must meet several, often contradictory, requirements: while good pressure tolerance and durability as well as gas tightness require thicker structures, good x-ray transmission can only be achieved with thin membranes. In this paper, the suitability of different window types for various applications is discussed. The applicability discussion is based on the results of tests performed on prototype windows, as well as on calculated and measured x-ray transmission properties. A comparative study of endurance vs transmission properties of some candidate membrane materials is also presented. Test results include pressure tolerance and leakage rates as well as some measurements of radiation damage to the window materials. The window technologies presented include coated polyimide membranes with two different supporting schemes as well as submicrometer beryllium membranes.
